Identification of the minimal portion of HSV-2(333) DNA that is necessary and sufficient to produce morphological cell transformation in primary rat embryo cells and Swiss 3T3 cells. Extension of this work to human cells and use of several different strains of HSV-1 and HSV-2 DNA. Establishment and passaging of transformed cell lines containing different segments of HSV DNA for the purpose of studying the role, if any, of the viral specified products in maintaining the transformed phenotype. Preparation of high specific activity radiolabeled probes of the herpesivirus "transforming gene" DNA, preferably in the form of seperated single strands suitable for use in high sensitivity screening of transformed cell lines and tumor tissues for the presence of viral DNA or RNA. Use of the high sensitivity probe DNA to test for possible specific sites of integration of the viral DNA into the host cell genome either within "fragment"-transformed lines or those already available that were produced using whole inactivated virus.